This invention relates generally to mammography, and more particularly, to a method and system for readily generating three-dimensional images based on tomosynthesis data derived from x-ray examination of a patient""s breasts.
Mammography is a low-dose x-ray procedure that creates one or more images of a patient""s breasts desirable for detection of early stages of cancer. FIG. 1 illustrates one example of a prior art mammography machine 10. Mammography machine 10 generally includes an x-ray tube 12 attached to an arm 14, which arm 14 is pivotally attached to a support 16, and a film plate or digital detector 18 attached to an arm 20, which arm 20 is also pivotally attached to support 16. X-ray tube 12 and arm 14, and digital detector 18 and arm 20, are counterbalanced so that x-ray tube 12 and digital detector 18 may be easily manually pivoted, upwardly and downwardly, and locked in position at different angular orientations.
A typical mammography procedure takes approximately thirty minutes. The procedure generally includes obtaining two images of each of the patient""s breasts, one from above and one from the side. For example, separate images are obtained of each of the patient""s breasts with x-ray tube 12 and digital detector 18 disposed in a vertically orientated arrangement along axis A (i.e., cranio-caudal) as shown in FIG. 1. In addition, separate images are obtained of each of the patient""s breasts with x-ray tube 12 and digital detector 18 oriented at an angle, e.g., along axis B1 (i.e., medio-lateral oblique) for one of the patient""s breasts, and along axis B2 for the patient""s other breast.
During the procedure, the patient""s breast is compressed between a compression paddle 22, e.g., a piece of radiographically transparent plastic, and digital detector cover 18 to flatten the breast, thereby decreasing the thickness and spreading the breast tissue, making the breast easier to be imaged. In obtaining the images, either from above or from the side, x-ray tube 12 is generally aligned perpendicular or normal to film plate or digital detector 18. A physician or radiologist then reviews the images of the breast, i.e., mammograms, to identify any breast cancer.
While the above described procedure is one of the best methods of detecting early forms of breast cancer, it is still possible for the breast cancer to be missed by a physician or radiologist reviewing the mammograms. For example, breast cancer may be missed by being obscured by radiographically dense, fibroglandular breast tissue, which is superimposed on the structures of interest in the mammogram.
Tomosynthesis breast imaging, in which a plurality of images or projection radiographs are acquired as the x-ray source is moved in an arc relative to the stationary breast and a stationary digital detector, has been studied in an effort to improve early detection of breast cancer. By shifting, scaling, and adding the plurality of projection radiographs, it is possible to reconstruct any plane in the breast being imaged that is parallel to the detector, thereby xe2x80x9cremovingxe2x80x9d superimposed tissue from the structures of interest.
Visualizing micro-calcifications and masses, cysts, and other diagnostically relevant structures of the breast in a series of two-dimensional (2D) planes acquired from tomosynthesis breast imaging provides important diagnostic information. However, the volume of data is generally large and contains a considerable range of data content. Thus, radiologists essentially attempt to conceptually reconstruct these planes into a 3D structure by viewing approximately, for example, 60-80 images (usually 10 images for each cm of compressed breast thickness and each typically has a 2304xc3x971800 matrix size) which makes this task difficult and time-consuming.
Therefore, there is a need for a method and system to visualize the data in 3D (e.g. Volume Rendering) to readily generate three-dimensional images of a patient""s breast in order to aid in diagnosis of abnormal breast structures.
A method and system are provided for generating at least one three-dimensional image of an object volume. The three-dimensional image is generated by applying a selected 3D visualization technique (Volume Rendering, Surface Rendering, or the combination of the two) on the tomosynthesis data. The tomosynthesis data of the object volume is obtained by applying a suitable reconstruction algorithm to a set of projection radiographs acquired by an imaging device for irradiating the volume with radiation at a plurality of radiating positions. The imaging device generates a plurality of spaced-apart planar images through the object volume by executing a suitable reconstruction algorithm. This reconstruction algorithm is based on the projection radiographs derived by detecting radiation at the plurality of radiating positions.